Sunil Nijhawan is a nuclear safety engineer with decades of experience with Candu Reactors. He developed the software that is used to assess accident progression in Candu reactors. He is also pro-nuclear, as are many of the interveners that regularly have very serious concerns with our regulator the CNSC.
His intervention identifies two very serious problems with safety devices that are meant to protect people and the environment from radiation, but do to poor designs pose significant risks to the unsuspecting public.
He points to safety relief valves that are not sized properly and as a result will allow the primary heat transport system to uncontrollably over pressurize during a station blackout. The best-case scenario this design flaw will destroy the reactor from a pressure tube failure, but the radiation is contained (Three Mile island). The worst-case scenario is the steam generators fail and there is an early containment bypass with huge releases of radiation(Chernobyl/Fukushima).
His other concern is related to the amount of Passive Auto-catalytic recombiners (PARS). These are devices that do not require power to operate and they use a catalyst to turn Hydrogen into water. These are meant to prevent hydrogen explosions like the three reactors in Fukushima. While this sounds like a great idea he has found that there are not enough of them to handle the amount of hydrogen that will be produced. The catalyst get very hot if the concentrations get too high. It has been found during testing of these devices that when exposed to too high of concentrations of hydrogen they shoot flames out of the bottom of them and will become the ignition source of the hydrogen explosion with no way of turning them off. He contends we would be safer without them.
I have a lot of concerns about every aspect of nuclear power, but the concerns brought fourth by Sunil are what keeps me awake at night. If you have the stomach for it please read his submission where he discusses step by step what will happen during a station blackout at Point Lepreau. We should all be very concerned that the safety of the province relies on NB Power keeping the power on at Lepreau.